V(CO)7+: A capped octahedral structure completes the 18-electron rule

CHED 1052

Jay W. Dicke, Henry F. Schaefer III, hfs@uga.edu, and Nathan J. Stibrich, nstibrich@ccqc.uga.edu. Center for Computational Chemistry, University of Georgia, 1004 Cedar St., Athens, GA 30602
Molecular structures, relative energies, vibrational spectra and bond dissociation energies of the seven-coordinate, 18-valence-electron vanadium carbonyl complex, V(CO)7+, are predicted theoretically. A C3v symmetry capped octahedral structure is found to be the global minimum and its predicted CO vibrational frequencies range from 2023 to 2122 cm-1, generally consistent with experiment for known cationic carbonyl complexes. The lowest energy structure of V(CO)6+ is also determined, a triplet D3d structure. The resulting bond dissociation energy, De, for CO ligand loss is predicted to be 11 kcal mol-1 with B3LYP , in good agreement with experiment, or 30 kcal mol-1 with BP86.